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Successful retrofit of passenger lumbar on 2021 Model Y

Hi all,

I wanted to jot down quickly some notes on my successful passenger lumbar retrofit. I will edit with more details after I get some sleep. All in all, it took about an hour for me to figure out and take things apart and put them back together.

Decontented Model Ys have a the lumbar support frame and harness but lack the switch, pump, and control unit.

20211002_230707.jpg
I started with a 2020 Model 3 seat that I found on Craigslist for $100, and my original intention was to just swap the seats over. However, I had heard that the harness for the lumbar is still in place in the latest build Model Ys so I thought I'd try to retrofit first, as it's a lot less work, and my Y had slightly nicer seat switch trim with silver accents.

What you need:

Tools: Torx T15, 10mm socket, a plastic pry tool or even like a disposable chopstick would be fine (for pushing on the clip for the headrests), a trim tool (looks like a small flat crowbar with a notch cut out of it)

1. Lumbar assembly from Model 3 or Model Y, looks like this: (apologies for bad photo, was quickly taking pics as I went along)


20211002_230307.jpg


Make sure it includes the actual pump which has the red, green, and blue lines coming from it.

2. Passenger seat switch assembly with lumbar button. Does not need to match the model Y trim as you will be reusing the actual buttons except for lumbar from your Y. You also will not need the physical buttons except for lumbar for the same reason. The switch in your car does not have the contacts under the blank for a switch, hence your need for a replacement. Note that 2021 seat controls have a small silver edge on the buttons. You will reuse the cushion buttons but the lumbar will come from your replacement switch so it will not match the driver's side unless you get a switch from a 2021. You probably don't care, but worth noting.

Steps to remove lumbar.

1. Raise your headrests. If you push down on the trim around your headrest posts you will see two clips that you push to the left to release the post, you will have to move the post up a little to keep it from clipping back in. This YouTube video shows the procedure:
The service manual also has the procedure. They do not have to be fully removed, just mostly up.

2. Remove the backrest trim. I just put my hands behind the top of the trim and pulled gently. If it is not coming out pull up the headrests more, as they old in the trim on the top. It is hooked in the bottom a pair of plastic hooks, so just hinge the trim back and lift out and set down. The bottom fabric flap is held in by elastic straps that are a pain to reach so I did not bother unclipping. You won't need to for acces.

3. On the back of the seat you will see the yellow lumbar frame. Our seats simply have the inflatable cushions and pump removed, there is no additional padding to make up for it, but the frame makes this effectively a seat with lumbar set to minimum.

20211002_224050.jpg


4. On the bottom of the frame you will see a single center 10mm bolt. Before removing, you'll see an elastic clip of fabric around the bolt. Lift and unclip the fabric, then undo the bolt.

5. On the left, the recliner motor connector needs to be disconnected, there is a release on the back of the connector that you can squeeze and the connector should just pull out. The harness for this motor also has two other connectors that are not connected to anything. A larger two row control unit connector and a four pin pump connector. The harness is clipped into the lumbar frame in two points. Use your trim tool to disconnect the clips from the frame. It is held in on both sides so simply get the tool under the clip and rotate it clockwise and counter clockwise and it will release.

6. Lift the lumbar frame towards the top of the seat so that the bottom clears the metal frame of the seat, then pull the lower part of the frame out and down to get it out. This is obvious once you see how the frame is mounted. You may need to press on the padding to get the frame to move.

7. Take your complete lumbar assembly and install it. connect the pump and control unit and the recliner, but do not clip the harness into the frame yet. the pump just fits into the empty space in the right bolster.

8.Raise your seat and move it forward enough to expose the T15 bolt you can see underneath the front right corner of the seat. Remove the bolt. Then pull the lower and upper cushion seat controls straight out from the switch. You may need to use a plastic trim removal tool to get under the switches to gently pry all around to get them to release.

9. Gently tug on the front corner of the seat trim, it should release, and the trim is also clipped in behind so as you tug it should come off as well. There is no need to disconnect the seat belt from the pretensioner on the seat, which you may have seen in the service manual.

10. From the back of the switch assembly pull out the harness. Connect the harness to the new switch you acquired and confirm the lumbar support works. Make sure the car is powered on (screen is on) as lumbar will not operate otherwise, even though the seat will. Disconnect the harness for now.

11. Remove the 3 Torx T15 screws holding in the old switch assembly and replace with the new, reuse your screws to secure them. Reattach harness and switch buttons and confirm operation. Reinstall seat trim and the screw in front from underneath.

12. Reattach the harness to the lumbar frame and take the seat back and reinstall it by hooking in on the bottom first (you may need to pull outwards on the cover at the bottom to clear the hinges) and then snapping in on top. Lower headrest all the way and you are done!

20211002_235105.jpg
 
Last edited:
this is awesome. does passenger seat settings get saved with driver profiles? if so, does this work with the profile?
The lumbar support has no sensors for recording state, so they have no memory capability, which is pretty normal. AFAIK there's no memory feature for the passenger seat, but even on the driver's seat there is no memory function for the lumbar support.
 

EVer Hopeful

Active Member
Jul 7, 2021
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AFAIK there's no memory feature for the passenger seat, but even on the driver's seat there is no memory function for the lumbar support.

That would make sense because while a specific driver would probably have the same (if any) passenger on most journeys, it's not a guaranteed occurrence so having memory on that seat could be more annoying than anything else

...plus, you wouldn't want your girlfriend's settings getting saved then the next day have your wife sit there :oops:
 
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@osunick thanks for posting this! I plan to do this retrofit for my dad. I ended up finding the parts on ebay for about $150. For the seat switch was it easy to pull off the recline and sliding button to add to the new switch? I'm nervous to pop them off as it seems the ones on ebay either have broken tabs on the switch and it makes me wonder if it's hard to remove the seat buttons?
 
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@osunick thanks for posting this! I plan to do this retrofit for my dad. I ended up finding the parts on ebay for about $150. For the seat switch was it easy to pull off the recline and sliding button to add to the new switch? I'm nervous to pop them off as it seems the ones on ebay either have broken tabs on the switch and it makes me wonder if it's hard to remove the seat buttons?
I did not find it hard at all, I used a plastic trim tool and just carefully pried around the edges. One side will release and then the other. What I imagine is happening is that the wreckers are just yanking out the switch assembly from the back of the trim without first removing the buttons, and that could do some damage.
 
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The lumbar support has no sensors for recording state, so they have no memory capability, which is pretty normal. AFAIK there's no memory feature for the passenger seat, but even on the driver's seat there is no memory function for the lumbar support.

so does this mean tesla wont be able to track how often the lumbar support is used - aka was elon talking fully out of his ass? or only partially?
 
so does this mean tesla wont be able to track how often the lumbar support is used - aka was elon talking fully out of his ass? or only partially?
The buttons almost certainly send out signals via LIN bus, so Tesla can likely tell how often the control is manipulated, just not the current state of the air cushions.
 
I ordered all the stuff for my car new from Tesla cheaper than eBay. I wanted the save revision that would have came on our car that way Tesla would have to prove that the retrofit actually caused a problem. Our was built 1 day after they decided to remove it!
 
Share some tips on how to get the parts, I think that’s useful info, I can even add it to the original post!
I just went into the service center and was like yo I need these parts lol.

1118494-00-G this was the lumbar that matched my driver side. And this was the switch 1098530-00-F.

Tips: you don’t need to remove the seat belt clip. Raise the seat all the way up and back you can remove the white retaining pin from underneath
 
I just went into the service center and was like yo I need these parts lol.

1118494-00-G this was the lumbar that matched my driver side. And this was the switch 1098530-00-F.

Tips: you don’t need to remove the seat belt clip. Raise the seat all the way up and back you can remove the white retaining pin from underneath
Nice, I see you can look up part numbers on the Tesla site but there's no purchase option, so that is super useful. Also, I didn't remove the seat belt clip, if you remove the front screw the trim flexes enough that you can easily access the screws on the switch assembly.
 
Nice, I see you can look up part numbers on the Tesla site but there's no purchase option, so that is super useful. Also, I didn't remove the seat belt clip, if you remove the front screw the trim flexes enough that you can easily access the screws on the switch assembly.
Yea that’s what I did I just went in to the service center and ordered the parts. Of course I got the well you know there are no returns and you fry your car blah blah
 
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